Process for dyeing only the flesh side of chrome-tanned fur skins



Patented Jan. 22, 1952 PROCESS FOR DYEING ONLY THE FLESH SIDE OF CHROME-TANNED FUR SKINS Ernst Liischer and Albert Engeloch, Basel, Switzerland, assignors to Sandoz A. G., Basel, Switzerland, a Swiss firm No Drawing. Application August 26, 1949, Serial No. 112,646. In Switzerland August 30, 1948 3 Claims. (01. 8-10) The present invention relates to a method of dyeing fur skins with reserve of the woolor hairfur, which method consists in that lamb, sheep, or other hair skins which have been preferably or exclusively tanned with chromium compounds and the flesh side of which is gently buffed are dyed, preferably at a temperature of 40-50 C., in an aqueous solution in the presence of capillarily active organic compounds with preferably substantive dyestuffs dyeing only the flesh side.

Fur skins are obtained by this process the flesh side of which is dyed while the woolor hair-fur remains undyed. If this latter has also to be dyed it can be done by using suitable dyestuffs in the same or in a fresh bath.

If an equal or two colour effect is desired wherein leather and woolor hair-fur are to be dyed equally or differently respectively it is preferably done by addition of acetate silk dyestuffs to the dyebath.

As capillarily active organic compounds there may be used: soaps and synthetic capillarily active organic substances, for example alkylbenzene and alkylnaphthalene sulfonic acids, fatty alcohol sulfonates and fatty acid condensation products such as oleic methyltauride, the oleic esters of hydroxyethanesulfonic acid and the sulfonates of glycerol-monooleate esters. These products are added to the baths in amounts of 0.25-3 grams per liter of dyebath.

The pretreatment of the leather preceding the dyeing operation, namely the milling of the undyed furor hair-skins, is conveniently done in a bath which also contains capillarily active compounds, such as for instance those mentioned above. The subsequent dyeing of the leather can be effected in a fresh bath or in the pretreating bath itself.

As dyestuffs preferably those substantive dyestuffs are used which themselves exert a good reserving action on the wooland hair-fibres and which dye the leather well.

If a more penetrating dyeing is desired it can be obtained by adding ammonia to the dyebath until the pH-value amounts to 9.2 at most and by acidifying the dyebath shortly before dyeing is completed until a pH value of 3.3 at least is reached. 1

In casewhere greater lots are to be dyed th dyebath can further be used after the consumed amounts of dyestuffs and thecapillarily active substances have been supplied. If a dyebath which, in view of a more penetrating dyeing, is first rendered alkaline and then acid, is desired for another bath it must also be adjusted by means of ammonia to a pH value of 9.2 at most.

The following examples without being. limitative in any way show how the above process may be carried out in practice.

' Example 1 75 pieces of sheep skins of a medium size gently buffed on the fieshside and tanned in the conventional way exclusively or preferably with chromium compounds were placed in a paddle of 1000 litres of water at a temperature of 35 C. containing 0.5-1 gram/litre of lauryl alcohol sulfonate, agitated for a short time and then allowed to remain in the dyebath over night. On the next day the skins were pulled through squeezing rolls or centrifuged. The thus pretreated skins were now put in a paddle containing 1000 litres of water at 48 C. and 1.5-2 grams/litre of lauryl alcohol sulfonate where they were agitated for I about 5 minutes. Now an aqueous solution of 1 kilogram of "Solar Brilliant Red BA" (Color Index No. 621; Schultz Farbstoiftabellen No. 706) was added while agitating, and the materials dyed for 15 minutes. The skins were then drawn through squeezing rolls, thoroughly rinsed in a paddle with running water, centrifuged and dried. After having placed them in damp saw dust the skins were staked and brushed on the flesh side.

In this way an even yellow dyed fieshside with undyed wool was obtained.

. Example 2 skins were pretreated as described in Example 1, but left in the paddle. After addition of 1 kilogram of lauryl alcohol sulfonate the water was warmed, while agitating, to a temperature of 48 C. An aqueous solution of 1 kilogram of Derma Brown R (Color Index No. 518; Schultz Farbstofitabellen No. 510) was then added whereupon the further treatment was carried out as indicated in Example 1.

Example 3 'With a view to obtain a more penetrating dyeing, skins having been pretreated in the way disclosed in Example 1 were placed in a paddle which contained 1000 litres of water of 48' 0., 1.5-2 grams/litre of an alkyl phenyl polyglycol ether and 1 gram/litre of dyestufi and which was adjusted by means of ammonia to a pH of 9. It was dyed for about 25 minutes, but for at most 30 minutes. Afterwards the dyebath was acidified by means of formicor acetic-acid until a pH value of 3.5 was reached, whereupon the goods were again dyed for 5-10 minutes. The further treatment was carried out according to Exampie 1.

What we claim is:

1. In 9, process of dyeing a. chrome tanned fur skin with reserve of the fur, the flesh side only being dyed, thestep of dyeing the chrome tanned fur skin with a substantive dyestufl' in an aqueous solution containing a capillarily active substance selected from the group consisting of soap, oleic methyltauride, the oleic ester of hydroxyethanesulfonic acid, glycerolmonooleate ester sultonate and lauryl alcohol sulfonate at a temperature of 40 to 50 C. whereby the fur remains undyed while the flesh side is dyed.

2. In a process of dyeing a chrome tanned lamb skin with reserve of the wool thereon, the flesh side only being dyed, the step of dyeing the chrome tanned lamb skin with a substantive dyestufi in an aqueous solution containing a capiliarily active substance selected from the group consisting of soap. oleic methyltauride, the oleic ester of hydroxyethanesulfonic acid, glycerolmonooieate ester sulfonate and lauryl alcohol sulfonate at a temperature of 40 to 50 C. whereby the wool remains undyed while the flesh side is dyed.

' ester sulfonate and lauryl alcohol sulfonate at a temperature of to 0., whereby the wool remains undyed while the flesh side is dyed.

ERNST Liiscnma. ALBERT ENGELOCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,968,795 Bertsch July 31, 1934 2,183,752 Mendoza Dec. 19, 1939 2,228,369 Schoeller Jan. 14, 1941 2,254,965 Kling Sept. 2, 1941 FOREIGN PATENTS Number Country Date 493,781 Great Britain Oct. 14, 1938 OTHER REFERENCES Chem. Trade Journal for September 1, 1933, page 155. 

1. IN A PROCESS OF DYEING A CHROME TANNED FUR SKIN WITH RESERVE OF THE FUR, THE FLESH SIDE ONLY BEING DYED, THE STEP OF DYEING THE CHROME TANNED FUR SKIN WITH A SUBSTANTIVE DYESTUFF IN AN AQUEOUS SOLUTION CONTAINING A CAPILLARILY ACTIVE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF SOAP, OLEIC METHYLTAURIDE, THE OLEIC ESTER OF HYDROXYETHANESULFONIC ACID, GLYCEROLMONOOLEATE ESTER SULFONATE AND LURYL ALCOHOL SULFONATE AT A TEMPERATURE OF 40 TO 50* C. WHEREBY THE FUR REMIANS UNDYED WHILE THE FLESH SIDE IS DYED. 